The upcoming ‘Doctor Who’ Christmas special is no doubt filling fans with mixed emotions as it draws closer. While many are excited to see the debut of new Doctor, Jodie Whittaker, the episode will also bring about the last adventure for Peter Capaldi’s Twelfth Doctor, which makes the moment bittersweet.

However, the moment the Capaldi regenerates may not be the biggest tear jerker of the episode. Radio DJ Jo Whiley was on set for the last days of filming and has said that the scenes before that transition are even more emotional as the Doctor says his goodbyes. Whiley said:

“The storyline is just fantastic – it’s so brilliant, it’s really really really clever. I don’t know what I can and can’t say – as is always the case with Doctor Who!”

When asked whether she’d seen the actual regeneration, Whiley said:

“It was leading up. Leading up to that moment. When he had to say some emotional farewells.”

While it is safe to say we will see a goodbye between The Doctor and Bill Potts (Pearl Mackie), Whiley’s comments leave fans wondering if this means we’ll get to see the Twelfth Doctor revisit some of his former companions before regenerating.

This would not be a new concept for the regenerating Doctor. When David Tennant’s Tenth Doctor regenerated into Matt Smith’s incarnation, he visited many of his old friends in an episode that also served as a farewell to then-showrunner Russell T Davies. With Steven Moffat leaving to make way for Chris Chibnall, who’s to say he wouldn’t also want to revisit some of the characters he’s created over the last seven years?

Whatever the case for companion cameos may be, Whiley was confident that fans would be making good use of their Kleenex by the end of the episode. She explained:

“[The set] was loaded with sadness and emotion. It’s fascinating to watch. As actors, they’re obviously all incredibly close, and the whole team are incredibly close. Doctor Who is such a close-knit family. Seeing them then become those characters, you just get drawn into what you’ve been watching on screen throughout the whole of this Doctor’s incarnation. It’s fascinating to see. And then they just snap out, and they’re the actors again. But you really did feel the intensity of what they’re going through. The fact that they are, as people, saying goodbye to each other. I think the viewers are going to be in bits when they watch.”

Whiley concluded:

“I think it will be a Blue Christmas. Peter’s such an amazing actor. Such an incredible actor. And I think ‘Doctor Who’s’ very lucky to have had him as one of the Doctors. And this is just such a great way for him to go out. It’s really fitting I think, the story is really fitting for him. Because it really calls on his great acting.”